Prepare the Meatballs: Preheat oven to 375°F (190°C). Line a baking sheet with parchment paper.
In a large mixing bowl, combine ground beef, breadcrumbs, egg, green onions, garlic, soy sauce, sesame oil, ginger, and brown sugar. Mix well until evenly combined.
Form the mixture into 1-inch meatballs and place them on the prepared baking sheet.
Bake for 18-20 minutes or until cooked through and golden brown.
Make the BBQ Sauce: While the meatballs are baking, whisk together soy sauce, honey, rice vinegar, sesame oil, and gochujang in a small saucepan.
Heat over medium heat until it starts to simmer. Stir in the cornstarch mixture and cook until the sauce thickens, about 2 minutes. Remove from heat.
Prepare the Spicy Mayo Dip: In a small bowl, mix mayonnaise, sriracha, and lime juice until smooth.
Assemble and Serve: Toss the cooked meatballs in the BBQ sauce until coated. Serve warm with the spicy mayo dip on the side.